1-aminoalkyl-3-carbolines



Patented Aug. 31, 1954 1-AMlNOALKYL-3-CARBOLINES Robert R. Burtner, Skokie, 111., assignor to G. D. Searle & 00., Chicago, 111., a corporation of Illinois No Drawing. Application April '13, 1953, Serial No. 348,579.

9 Claims. 1,

This invention relates to dialkylaminoalkylcarbolines, their acid addition and quaternary ammonium salts, and processes for the manufacture of these carbolines and their salts. In particular this invention relates to S-carboline derivatives of the formula than 4 carbon atoms; 'NRR" is either a lower dialkylamino radical or a nitrogen-containing heteromonocyclic radical; X is one equivalent of an anion; and n is either'O (where the compound is a tertiary base) or it is .1 (where the compound is a quaternary ammonium salt or a salt comprising one molecule of tertiary base plus one equivalent of an acid) or it. is 2 (where the compound comprises one molecule of base plus two equivalents of an acid).

In the compounds of the foregoing formula, Alk represents an alkylene radical such as ethylene, propylene, butylene, trimethylene, tetramethylene, and like bivalent radicals derived from saturated aliphatic hydrocarbons containing from 2 to 4 carbon atoms. The radical R. represents either. hydrogen or a lower alkyl radical such as methyl, ethyl, propyl, isopr-opyl, butyl. isobutyl, and secondary butyl. The radicals R and R" represent lower alkyl radicals of the foregoing type; or, taken together with the attached nitrogen, they represent saturated, nitrogen-containing, heterocyelic radicals such as piperidino, morpholino, and pyrrolidino radicals. The substituent X represents one equivalent of an anion as remarked, and includes such non-toxic anions as chloride, bromide, iodide, methyl sulfate, ethyl sulfate, benzenesulfonate, toluenesulfonate, tartrate, succinate, malate, acetate, citrate, nitrate, sulfate, phosphate, sulfamate and the like.

The compounds of this invention are useful chemotherapeutic materials in the field of cardiac pathology. In particular, they are valuable because of their digitalis-like activity, showing marked capacity for myocardial stimulation in instances of insufficiency associated with the failing heart.

The amine bases which comprise thisinvention are relatively insoluble in water, but may be dissolved in dilute acids and in most of the common organic solvents. The acid addition and quaternary ammonium salts of this invention are, on the other hand, readily soluble in water and in aqueous solutions of alcohols or other watermiscible organic solvents. The subject compounds may be administered in solid form as tablets or capsules; dissolved in aqueous media they may be given .parenterally.

The compounds to which this invention relates are conveniently prepared starting with the appropriate 3-carboline, which may be obtained by the method of Freak and Robinson as reported in the Journal of the Chemical Society, 1938, 2014. The 3-carboline is reacted, successively, with a condensing agent, such as sodamide, and a dialkylaminoalkyl halide, for example 'diethylaminoethyl chloride, to produce the corresponding 1 dialkylaminoalkyl-3-carboline. Various inert, non-polar, organic liquidswill serve as reaction media, toluene having been found a solvent of choice when sodamide is the condensing agent. With potassium carbonate, methyl ethyl ketone may be used. The reaction is commonly run at temperatures of to centigrade and completed after approximately 20 hours. Temperatures of the order of 20 higher or lower may also be used, and the reaction time may vary from 10 to as long as 36 hours. An inert atmosphere, such as a nitrogen atmosphere, is ordinarily maintained throughout the course of the reaction, though this may be dispensed with after the first two or three hours. The l-dialkylaminoa1ky1-3-carbo1ine thus formed, the formula of which is lkN where Alk, R and R" have the meanings hereinbefore defined, may then be converted to the acid addition salt by simple admixture with one or two equivalents of any of various inorganic and strong organic acids, the anionic portion of which conforms to the definition of X as set forth above. Alternatively, the said l-dialkylaminoalkyl-3-carboline may be quaternized by addition of an alkyl ester of the formula where R and X have the meanings hereinabove assigned. Quaternization takes place in the temperature range to 50 centigrade, using an inert solvent such as chloroform, acetone, methyl ethyl ketone, methanol, butanol and the like. The reaction is ordinarily completed in from 12 to 48 hours and is generally carried out in a closed system if a lower alkyl halide, such as methyl chloride, is one of the reagents. Using methyl chloride, the reaction may be smoothly effected in chloroform solution at 25 centigrade for 24 hours.

The following examples will illustrate in detail certain of the carboline derivatives which constitute the present invention, and methods which have been devised for their preparation. However, the invention is not to be construed as limited thereby either in spirit or in scope, since it will be apparent to those skilled in the art of organic synthesis that many modifications, both of materials and of methods, may be practiced without departing from the purpose and intent of this disclosure. In the examples hereinafter detailed, temperatures are given in degrees centigrade C.), pressures in millimeters (mm) of mercury, and relative amounts of materials in parts by weight, except as otherwise noted.

Example 1 A. i-(fi-diethylaminoethyl) -3-carboline.-To a stirred suspension of 39 parts of sodamide in 3500 parts of dry toluene at 530-100 C. under an atmosphere of nitrogen is added 170 parts of 3-carboline. The reactants are refluxed and stirred for approximately three hours, by the end of which time the evolution of ammonia is found to be practically completed. Heating is discontinued, and 135 parts of ,B-diethylaminoethyl chloride is then slowly added at a rate such that moderate refluxing continues. Heating is resumed as required to maintain reflux temperatures for 15 hours. Approximately 4000 parts of water is then added, whereupon the toluene layer is, successively, separated, washed with water, and subjected to vacuum distillation to remove the solvent. The clear brown oil which remains is the desired 1- 3-diethylaminoethyl) -3-carboline.

B. 1 diethylaminoethyl) 3 carboline dihydrochloride.-The base of the foregoing part A is converted to the hydrochloric acid salt by dissolving in 2100 parts of anhydrous ether and treating with two molecular equivalents of absolute alcoholic hydrogen chloride solution. The dihydrochloride, which granulates on standing, is recovered on a, funnel, rinsed thereon with ether, and finally dried at 75 C. in that order. Crystallization from 2800 parts of absolute alcohol, using decolorizing charcoal in process, gives white crystals of l-(fi-diethylaminoethyl)-3-carboline dihydrochloride, M. P. 230-23l C. The material is readily soluble in water.

C. 1 3 dieth'ylaminoethyl) 3 carboline methobromide.A solution of 117 parts of l-(fidiethylaminoethyl)-3carboline, prepared according to the technique of part A of this example, and 41 parts of methyl bromide, in 750 parts of dry chloroform, is allowed to react in a closed system for 24 hours at 25 C. The solvent is then stripped in vacuo, leaving a viscous residue which is taken up in 2100 parts of anhydrous ether. The crystalline quaternary compound forms on standing. It is recovered on a funnel, rinsed thereon with ether, and finally dried in vacuo over sodium hydroxide. The pale yellow quaternary salt thus obtained melts at 155 C. Crystallization from 9 volumes of a mixture of 35 parts of isopropyl alcohol and parts of ethyl acetate, using decolorizing charcoal in process, gives colorless crystals of l-(fidiethylaminoethyl)-3-carboline methobromide, M. P. l55156 C. The product is quite soluble in water. It has the formula CzHs - CHsBI Example 2 A. 1 (4' methyl 2' pyriclyl) benzotriazoZe.-A mixture of 86 parts of 2-bromo-4- methylpyridine, 54 parts of o-phenylenediamine, and 2 parts of copper powder is heated in a jacketed vessel for 4 hours at -155 C. (jacket temperature) under an absolute pressure of 40 mm. of mercury. The mixture, which refiuxes gently at first, gradually becomes more viscous and ceases reflux as the reaction progresses. The semisolid product is dissolved in 260 parts of hot alcohol; and 1250 parts of 10% aqueous hydrochloric acid is then added, whereupon the copper is filtered out, and a solution of 63 parts of sodiu-m nitrite in 630 parts of water is then added very slowly at 5-10 C. to the stirred filtrate. Following addition of the sodium nitrite, stirring is continued for 1 hour longer at 5 0., after which the reactants are allowed to warm to 25 C. overnight. The gray precipitate which has formed is, successively, recovered on a funnel, rinsed thereon with water, and dried at 25 C. The product thus obtained is 1-(4'-methyl-2'- pyridyl) -benzotriazo1e, M. P. 117-118" C. Crystallization from 20 volumes of methanol gives pale gray needles, M. P. 118 C.

B. 6-methyZ-3-carbolina-A stirred solution of 81 parts of the triazole of the preceding part A in 700 parts of phosphoric acid is cautiously heated to C. Moderate evolution of nitrogen occurs. Temperature of the reactants is slowly increased to 200 C. over a period of 30 minutes, by the end of which time nitrogen evolution practically ceases. The materials are heated and stirred for 15 minutes longer at 200- 205 C., at which point the mixture is cooled to 25 C., and a hot solution of parts of picric acid in 2000 parts of alcohol, followed by 830 par-ts of hot water, is then added. Refrigeration overnight promotes precipitation of the picrate, Which is filtered off and then suspended in 4800 parts of 8% aqueous caustic soda at approximately 75 C. The crude methylcarboline which separates is recovered on a funnel and rinsed thereon with hot water until the washings are substantially free of color. Upon drying at 75 C., a gray amorphous powder is obtained which is subjected to continuous extraction with 400 parts of boiling alcohol for 24 hours. Upon separating and cooling the extract, brown crystals are precipitated which, recovered on a funnel '55 and dried at "75 "6., show 4P. 22122-213 16. *A further 320- parts ot'alcohol is-addedto the :exftraction residue, and :the'mixture is allowed to hoiliforzZUminutes. The mixturesis then filtered,

and this filtrate is :cnmbinedxwith that from the precipitation above. Vacuum -=corrcentrationiof the-acombinedrfittrates itozabout one-tenth the acriginalryolume :gives: a second crop. of :crystals, pale yellow in color,.216--.C;. Recrystallization of the 2 crops of crystals from 40 volumes of methyl alcohol gives'nearlyacolorless*6methyl 3-carbo1ine, M. P. 215 C.

C. 1 (.13 diethylamm'oetliyl) 6 methyl 3-carb0 Zine.-Using essentially the procedure of Example 1A, 55 parts of the above 6-methyl-3- carboline,. 12..par-ts"of sodamide, and 41 par-ts of fl-diethylaminoethyl chloride, in 1750 parts of dried toluene, are reacted at reflux temperatures for 24 hours to produce in good yieldtl-Kfi- -diethszlanrincethyt) fimrethYl-Becarholine.

D. 1 (.13 diethylammoethyl')" -46. -tmethyl'- 3-carboline dz'hydrochlo'ride.Preparation of the dihydrochloride .o'f l1-(,8-idiethylaminoethyl)-6- methyl-3-carboline is carriedE-out in anhydrous ether solution using two equivalents of absolute A /O.1Hs. amon -N toanmso;

can;

Example 3 A. 1 (B dz n butylaminopropyl) 3 carboline.-To a stirred suspension of 78 parts of sodamide in 7000 parts of benzene at reflux temperature under a nitrogen atmosphere is added 340 parts of 3-.carboline. Refluxing is continued, with stirring, until evolution of ammonia gas ceases-which is usually after about hours. .Aatithis pointheating is temporarily discontinued while 500 parts of B-di-rH-blltYlQ'HliHO- .propyl chloride is slowly added, .following which heat'is again applied and reflux maintained,-w1th stirring, for 24 hours. Approximately 18.0.00 parts of water is then .added, whereupon thefbenzene layer is, successively, separated, Washed with water, and subjected to vacuum distillation to remove the solvent. The residual dark viscous oil is the desired 1-(B-edi-nwbutylaminopropyl)- 3-carboline.

B. 1 (B dz n bwtylaminopropyl) 3 carboline dihydrochloride.-Conversion of the base of the preceding part A of this example to the hydrochloric acid salt is accomplished according to the technique :offExample .113 :by dis.- solving: 247 parts of :the said base: :21003parts of anhydrous ether and reactingthis solution with *two molecular equivalents. :of absolute al coholic hydrogen chloride solution. The .-1-.(-fl-:di n-butylaniinopropyl)13-ecarboline dihydrochloride ithus eobtained isrmo'deratelysolubleain water.

C. .1 .(B iii nebutylaminopropyl) -:3 'cwrholine ethiodider-Following the procedures of Examples, 1C and 2E, 1--.( cedi-n-butylamino -propyl- 3-carbolinezis quaternized by reacting 337 ,parts zthereof together with 156. 'parts of ethyl iodide in 1450 .parts iofidryichloroform, maintaining the reagents in a closed system -to prevent evaporation losses. After 24 hours, the solvent is stripped in vacuo;.-andr4500 parts of anhydrous ether is then: added. The desired product is obtained as a viscous oil which ,granulates on standing. It has theformula .A. 1 (6' methyl .2 pyridyl benzotriazoZe.A mixture of l-79-parts of 6-methyl-2- .bromopyridine and .112 parts of 'o-phenylenedi- .amine is .heated in the presence of. 4 parts of copper :powder according .to the technique detailed in ExampleZA. The reaction product- .following addition .of 525 parts of hot alcohol, acidification with 2500 parts .of .10 aqueous .hy- .drochlonic acid, and filteringout-of .thecopperii'S diazotized with l25=1oarts .of. sodium nitrite to give, .in. goodyield, the desired -1-( 6'-.methyl-2"- pyridyl)--benzotriazole; M. P. fi l- C.

-B. 4-methyl-.Zi-carboline.FolloWing the procedure of Example 2B, 165 parts of l-(6methyl.- 2-pyridyl)-benzotriazole:and 1410 parts of 85% phosphoric acid are reacted together; and the product is treated withsa hot alcoholic solution of pioric acid to give the crude carboline picrate. The picrate is treated with 8% aqueous caustic soda to yield thecrude methyilcarboline which is, in turn, first' extracted-for 1 5 minutes with 2400 parts of boiling alcohol, and then, following precipitation (on cooling) and recovery from this extract of an initiarcrop of crystals melting at 254N255" C..',.:is..-re-.extracted for '10 minutes with the boiling crystallization mot-her "liquors to give, :on'vacuumconcentration :to one-sixth the -.origi :nal volume, an additional crop of crystals, .P. 255 aC. Hie desiredJ4-methyl-3-carbo1ine obtained :in theform of pearl gray iplates.

G. 1-03 :diethylaminoethyl)--4-methyZ-3-ccr-' boZine.In accordance with the procedure detailed in Example 2.0, interaction of parts of 4-:methyl-3ecarbohne, 31 v partsof sodamide, and 108 ,parts of fl-cliethyla-minoethyl chloride, in 435 parts of xylene, gives ajgoodyield of :1-( ii-diethyl- .aminoeth-yl")-4-methyl-3-carboline as -a dark oil.

I9. 1- (.18 ---dietitylaminoethyl) -4-methyZ3-'carboline dihydrochZoride.The oily base of Exam- .ple 14C is \converted to the hydrochloric :acid addition salt in conventionalcfashion by treatment with two :equivalents 'of absolute alcoholic hydro- ,gen- :chloride solution. Crystallization of the crude .dihydrochloride :from :1-1 volumes otabso- 7 lute alcohol, using decolorizing charcoal in process, gives colorless crystals of 1-(B-diethylaminoethyl) 4 methyl 3 carboline dihydrochloride, M. P. 237-238 C. The product is moderately soluble in water.

E. 1-(5 diethylaminoethyl)-4-methyZ-3-carb'olz'ne methobromide.-Using the procedure of Example 1C, the quaternary ammonium salt of the foregoing 1-(5-diethylaminoethyl)-4-methyl- 3-carboline is obtained, following crystallization from a mixture of isopropyl alcohol and ethyl acetate, as pale yellow crystals, M. P. 142-143 C. The product is quite soluble in Water. It has the formula CzHt CH2CH2N -CHaBr Example 5 A. 1-(5 diethyZaminoethg l)-5-carboline.-By the method of Example 1A, 6'7 parts of 5-carboline-prepared according to the method of Robinson and Thornley described in the Journal of the Chemical Society," 1924, 2170-2172--16 parts of sodamide, and 54 parts of B-diethylaminoethyl chloride, in 350 parts of dry xylene, are reacted together to give 1- (B-diethylaminoethyl) 5-carboline as a viscous oil.

B. i-(B-dz'ethylaminoethyl) -5-carboline dihydrochZoride-The 5-carboline base of the preceding part A is converted in conventional fashion to the hydrochloric acid addition salt using two equivalents of absolute alcoholic hydrogen chloride solution in anhydrous ether medium. Following crystallization from approximately 30 volumes of absolute alcohol, colorless crystals of 1-(5 diethylaminoethyl) -5 carboline dihydrochloride are obtained which show M. P. 297 C. The material is quite soluble in water. It has the formula CzHs CzHs

Example 6 A. 4,5-benzo-1-(fi diethylaminoethyl)-3-ca1'- boZine.A mixture of 42 parts of 4,5-benzo-3-carbolineobtained by the method of Robinson and Thornley as reported in the Journal of the Chemical Society, 1924, 634-and 4350 parts of boiling xylene is reacted with 8 parts of sodamide under a nitrogen atmosphere, according to the technique of Example 1A. After 5 /2 hours, evolution of ammonia ceases, whereupon 27 parts of 3-diethylaminoethyl chloride is introduced; and the reactants are then maintained for 15 hours at reflux temperature. The product is worked up as before to give a good yield of 4,5-benzol-(fl-diethylaminoethyl) -3-carboline as a dark oil.

B. 4,5-benzo-l-(B diethylaminoethyl) -3-carboline dihydrochZoride.The base obtained in part A of this example is dissolved in 1100 parts of anhydrous ether, the solution is treated with decolorizing charcoal, and two equivalents of ab- 8 solute alcoholic hydrogen chloride solution is then added. The yellow dihydrochloride thus precipitated is, successively, recovered on a funnel, dried over sodium hydroxide in vacuo, and crystallized from 18 volumes of absolute alcohol to give tiny, pale yellow needles, M. P. 242-244" C. The product, 4,5-benzo-1-(B diethylaminoethyl) -3-carboline dihydrochloride, is only moderately soluble in Warm water. It has the formula I claim: 1. A member of the group consisting of compounds of the formula z\Nl wherein Z is selected from the group consisting of hydrogen and a methyl radical, Alk is a lower alkylene radical containing at least 2 and not more than 4 carbon atoms, and NRR" is selected from the group consisting of lower dialkylamino, piperidino, pyrrolidino, and morpholino radicals; non-toxic acid addition salts thereof; and quaternary ammonium salts of the formula CH2CH2N -RX wherein R, R and. R" are lower alkyl groups, and X is halogen.

3. 1 (p-diethylaminoethyl) 3 carboline methobromide.

4. A dialkylaminoethyl methyl 3 carboline acid addition salt of the formula I CHzCHz-N 9 re wherein R and R" are lower alkyl groups, and 6. 1 (,B-diethylaminoethyl) 4 methyl 3- X is halogen. carboline dihydrochloride.

5. A diethylaminoethyl methyl 3 carboline 7. 1 (,B-diethylaminoethyl) 6 methyl 3- dihydrochloride of the formula carboline dihydrochloride.

s. 1 (p-diethylaminoethyh s carbolin e dihydro-chloride. H30 I 9. 1 (B-di-n-butylaminopropyl) 3 car N dihydrochloride.

CzHs 10 No references cited.

CH2CH2N 21101 

1. A MEMBER OF THE GROUP CONSISTING OF CONPOUNDS OF THE FORMULA 